"As we reached near the house, they opened fire. Our force returned the fire and five militants were killed."

Al Jazeera's Imran Khan, reporting from Karachi, said the gun battle took place in a dangerous neighbourhood of Karachi.

"Many people fear going into that neighbourhood unless they can speak the local language which is Pashtun in that particular neighbourhood.

"It is a very difficult area for anybody who is not a member of that community to go into."

"The raids are adding to the ethnic tension that is already very high in Karachi."

Terror 'target'

Ali Dayan Hasan, a senior researcher in the Asia division of Human Rights Watch in Lahore, told Al Jazeera that Karachi is a soft target for terrorism.

But he dismissed accusations that the city's Pashtun community is mainly to blame for recent attacks in Pakistan.

In depth


 Tensions run high in Karachi
Talking to the Taliban
 The Pakistan Taliban

Pakistan's war

"Given Karachi's ethnic history and given its history of ethnic violence, it is very problematic that any group be targeted in this way or that they are seen being targeted in this way," he said.

Although the government is targeting the Pakistani Taliban in its operations in the northwest, Hasan said there are a number of other groups that pose a security threat to Pakistan.

"It's what we describe as a militant fault line that runs through Pakistan," he said.

"Members of these groups are not just from the Pashtun community, in fact in many instances members of some of these groups are from the Punjab. So the idea that Islamic extremism is the preserve of the Pashtun is incorrect."

'Taliban infiltration'

Fears have been growing over the past few months that Taliban fighters fleeing an army offensive in the country's the northwest are infiltrating into Karachi, the country's commercial capital.

The Pakistani military has in recent days expanded an operation against fighters in the North West Frontier Province to neighbouring South Waziristan, targeting bases reportedly used by Mehsud.

The military has been launching air raids on Mehsud's bases this month while soldiers have been securing main roads and sealing off his stronghold.

Mehsud is a close al-Qaeda ally and his followers have responded with a campaign of attacks, including suicide blasts, across the country.

On Friday, two soldiers were killed and several others wounded after a suicide bomber attacked an army vehicle in Pakistan-administered Kashmir.

It was the first suicide attack in the Pakistani part of Kashmir, according to Choudhry Imtiaz, a senior administrative official.